What is Uncategorised voicemail?

When you are using your free Optus voicemail and it asks you if you would like to return the call from within the Voicemail application this is considered a Premium Service and is an excluded call which you will be charged $1 per minute.

To avoid these charges simply listen to all of your voicemail messages and end the call and return the person back using your included calls which you will not be charged for.